1. Field of the Invention
This invention relates generally to membrane-type filtering devices.
2. Description of the Related Art Including Information Disclosed Under 37 CFR .sctn..sctn.1.97-1.99
In particular the invention relates to a membrane filtering device for the micro and ultra filtration of fluids by the crossflow method, with at least one membrane filter module containing capillary or hollow fiber membranes in the form of a bundle in a tubular filter housing, said membrane filter module having a pair of flow distributor heads attached to both filter housing ends and having flow distributor plates which are to be attached to the flow distributor heads and to line connectors that lead to the required operating devices intended to maintain a controlled fluid circulation through the membrane filter module, thereby to effect a controlled replenishment of the fluid to be treated and a discharge of the filtrate and of the substances being filtered out.
A membrane filtering device and a membrane filter module of the above described kind are known from WO 88/01895, for instance. In the membrane filter module known from this publication there is present at the two module faces only one access each to the respective bundle face, i. e. to the interior of the capillary or hollow fiber membranes. The access to the interior of the filter housing and to the outside of the capillary or hollow fiber membranes is located laterally on a side in the filter housing end area. Provision is made for the fluid to be treated to be fed into such lateral openings at one end of the filter housing and, after the fluid has passed the outside of the capillary or hollow fiber membranes, it is discharged, again at lateral openings at the other filter housing end.
The filtrate removed from the fluid is taken off at the bundle faces and transferred into filtrate lines connected thereto. But membrane filtering devices of this type have the considerable disadvantage that they can be operated only in a manner determined in advance. This applies in particular to applications in which the flow section or volume of the circulating fluid to be treated must be adjusted so as to be substantially greater than the flow section of the filtrate to be removed.
Similar situations and conditions also exist in hollow fiber dialysis machines such as known from DE-PS 30 23 681, for example.